Pvt.js - JavaScript Private Instance Members

pvt.js

/* Pvt.js - JavaScript Private Instance Members
 * By Adam Crabtree http://noderiety.com/
 * MIT Licensed.
 */

/**
* Generate a private member store
* @returns {function} The private member accessor function
*/
function Pvt() {
  // Lookup array for storing private member objects
  var store = [];

  /**
  * The private member accessor function
  * @param {object} The lookup object
  * @returns {object} The object's associated private member store
  */
  return function(obj) {
    // initialize the object's store
    if (typeof obj._pvt == 'undefined') {
    	
/*    REVISION #1 (See Below for Comments)

      obj._pvt = store.push({_self : obj})-1;

      REVISION #2
      
      // Generate random key
      while((_pvt += chars.charAt(Math.floor(Math.random() * 62))).length < 6);
      obj._pvt = {key: store.push({_pvt : _pvt})-1, hash: _pvt};

*/
    	
      obj._pvt = store.push({})-1;
    }

/*  REVISION #1
     
    // Ensure we have with the original object, not just an equivalent ._pvt 
    return store[obj._pvt]._self === obj ? store[obj._pvt] : null;  

    => Creates memory leak preventing obj from being garbage collected
    => Only fail-proof way to prevent object impersonation
    
    
    REVISION #2
    
    // Ensure object fingerprints match
    return store[obj._pvt.key]._pvt === obj._pvt.hash ? store[obj._pvt.key] : null;
    
    => Significantly decreases performance
    => Not fail-proof, but very difficult to fake
*/
    
    return store[obj._pvt];
  };
}